1. Field of the Invention
Aspects of the present invention generally relate to wireless communication systems. More particularly, embodiments of the present invention relate to a wireless communication system that provides telephone, data and Internet connectivity to a plurality of users.
2. Description of Related Art
Several systems are currently in place for connecting computer users to one another and to the Internet. For example, many companies such as Cisco Systems, provide data routers that route data from personal computers and computer networks to the Internet along conventional twisted pair wires and fiber optic lines. These same systems are also used to connect separate offices together in a wide area data network.
However, these systems suffer significant disadvantages because of the time and expense required to lay high capacity communications cables between each office. This process is time consuming and expensive. What is needed in the art is a high capacity system that provides data links between offices, but does not require expensive communication cables to be installed.
Many types of current wireless communication systems facilitate two-way communication between a plurality of subscriber radio stations or subscriber units (either fixed or portable) and a fixed network infrastructure. Exemplary systems include mobile cellular telephone systems, personal communication systems (PCS), and cordless telephones. The objective of these wireless communication systems is to provide communication channels on demand between the subscriber units and the base station in order to connect the subscriber unit user with the fixed network infrastructure (usually a wired-line system). Several types of systems currently exist for wirelessly transferring data between two sites. For example, prior art wireless communication systems have typically used a Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA) or Frequency Division Multiple Access (FDMA) type system to facilitate the exchange of information between two users. These access schemes are well known in the art.
As can be imagined, in any of these type of wireless communication systems there are many components that need to be adjusted and tuned so that the system can compensate for frequency shifts and atmospheric disturbances. For example, high or low humidity and temperature, or rain, snow and wind can affect wireless communication systems. Thus, what is needed in the art is a convenient system that detects temperature and/or power levels in the wireless communication transmission and automatically adjusts components within the system to provide for maximum data transmission efficiency.
Furthermore, on the base station side of many radio frequency systems, the gain of the receive (and transmit) path is not completely deterministic and not known in advance due mainly to differing amounts of cable length required to connect the roof-top radio and antenna to the indoor equipment. Like the transmit path, the receive path must be compensated (calibrated) in some manner to produce a known signal level at various points in the receive chain for optimal performance of the system. This compensation or path calibration is ordinarily done by sending a known signal level into the path and adjusting the gain(s) along the path until the signal level measured along the path is at the desired level. This obviously requires some sort of signal generator to produce the signal for this calibration process. In the base station, in the transmit direction, the signal generator could be the base station equipment itself. In the receive direction, there is no “built-in” signal generator for the calibration.
This problem can be solved in various ways, some of which are by using equipment external to the base station itself, by including a signal generator in the base station receive path hardware, or by using some sort of transmit signal loop-back scheme in the radio. All of these techniques incur some amount of additional expense and/or complexity in the base station design and/or installation. Thus, what is needed is a way to compensate for the differing cable lengths without incurring additional expense and/or complexity in the base station design and/or installation.
Furthermore, the output power stability of the roof-top radio may be directly affected by the gain of the transmitter circuits. The transmit power should be as high as possible to optimize range but not so high as to cause excessive signal distortion. Thus, what is needed is a way to control the transmitter power so as to provide an optimum transmit power to operate at under all conditions and that is not affected by modulation type.